Why I Hope There's No Life on Mars

We've already found water on mars, but finding organic inhabitants on our red neighbor would be the discovery of the ages. Columnist Glenn Harlan Reynolds worries that it would only make life on Earth more complicated.

Life on Mars! H.G. Wells got a good story out of the idea, and while the Martian life of Wells, Edgar Rice Burroughs and (more recently) Robert A. Heinlein and S.M. Stirling is exciting, it is also fictional. Still, many people hope that we'll find some sort of life on Mars for real, and that would be exciting, too--even though theselife forms probably wouldn't look much like Burroughs's "Princess of Mars," Dejah Thoris.

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But I hope we don't find any life there at all. I hope that Mars is as dead as a doornail. Even deader, since most doornails, in fact, harbor bacterial life. Dead as the moon, then.

Why am I such a spoilsport? Because life on Mars would make life on Earth a lot more complicated. First, imagine that there's no life on Mars. That means we can go there, as we did on lunar missions, with no serious worries about bringing back deadly germs. (We initially quarantined Apollo astronauts upon their return to Earth. But by Apollo 15 NASA had concluded that the moon was as lifeless as, well, the moon.) No concerns about bringing deadly bacteria home, and none about contaminating the moon with earthly bacteria that might mess up its biospheric ecology.

If Mars is equally lifeless, that will make exploring--and later settling--the planet much easier. We can go there and return without this particular worry, and we can introduce Earth life without concerns that we'll damage indigenous creatures. Astronauts won't have to be quarantined, and the environmental impact statement, or its interplanetary equivalent, will be easier to determine. On the other hand, if there is life on Mars, things get a lot tougher.

Worries about bringing Mars life to Earth are real. Life that's well-adapted to the Martian environment probably wouldn't be well-adapted to Earth, or coexist well with its inhabitants. That means that the Andromeda Strain scenario, in which Martian bugs infect and kill people, is very unlikely. But very unlikely isn't the same as impossible, and given the stakes, astronauts--or even robotically recovered soil samples--returning from Mars would have to be very carefully handled indeed to ensure that Earth didn't become contaminated.

Preventing contamination in the other direction is basically impossible, at least if humans travel to Mars. Human beings are germ condominiums--there are more bacteria living in your body than there are human cells, making you outnumbered in your own skin--and even if we're careful to bag and seal wastes, etc., a substantial degree of contamination is inevitable. It's unlikely that earthly bacteria could flourish on Mars, but again, we're not certain. While the consequences might not be as bad as the worst-case possibility of bringing Mars life to Earth, if earthly bacteria displaced Martian bacteria, it could greatly complicate scientific research. (Is that E. coli native to Mars, or just proof that some earthling had poor personal hygiene?) And if the earthly bacteria turn out to do well on Mars, they might lead to the extinction of indigenous species before we could even study them.

The 1967 Outer Space Treaty complicates things too. It requires signatories, which include the United States, to conduct explorations of celestial bodies "so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter." So preventing contamination of Mars--and the so-called back contamination of Earth by Martian germs--is not just a good idea, it's the law. In response to these requirements, NASA, the European Space Agency and other space agencies do their best to sterilize spacecraft bound for other planets and are already planning rigorous protection for samples returned to Earth.

Of course, the discovery of life on Mars would be a stunning scientific advance, solving once and for all the question of whether life is unique to our planet. But the price we would pay for that discovery might well be the loss of an entire new world for humanity. Mars is Earth's closest twin in the solar system, a planet that many scientists think could be modified to become a suitable second home for humankind.

Aerospace engineer Robert Zubrin has suggested that by thickening the Martian atmosphere and then introducing appropriate species, we could "terraform" the Martian environment into something more hospitable. Given the growing threats to human life here on Earth, I'd just as soon we had somewhere else to go, so that all of our eggs weren't in one fragile basket. Sure, the failure to find life on Mars would be a disappointment. But it would make it much more likely that the planet will brim with life--human life--some day in the future.